Abstract: FR-PO248
Optimizing Patient Enrollment in Clinical Trials Based on Albuminuria Inclusion Criteria
Session Information
- CKD: Clinical, Outcomes, Trials - II
October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 1902 CKD (Non-Dialysis): Clinical, Outcomes, and Trials
Authors
- Waijer, Simke W., University Medical Center Groningen, Groningen, Netherlands
- Mulder, Skander, University Medical Center Groningen, Groningen, Netherlands
- Provenzano, Michele, Second University of Naples, Naples, Italy
- Perkovic, Vlado, The George Institute for Global Health, Newtown, New South Wales, Australia
- Lambers Heerspink, Hiddo Jan, University Medical Center Groningen, Groningen, Netherlands
Background
Clinical trials in CKD enroll patients with elevated urinary albumin:creatinine ratio (UACR) levels to enrich the population for high renal risk patients. Screen failure rates are often high due to high intra-individual variability in UACR. We tested whether a screening approach with more flexible UACR thresholds would decrease screen failure rate without adversely impacting on overall study duration.
Methods
We performed a post-hoc analysis on data from the ALTITUDE trial. We selected patients randomized to placebo treatment with a baseline UACR >300 mg/g and eGFR between 30 and 60 ml/min/1.73m2 at the first visit (pre-screening). We then used stepwise lower UACR cut-offs at the next qualifying visit (e.g. 300 (base scenario), 210, 150, 30 mg/g) as inclusion criteria. For each scenario we calculated the number of eligible patients and number of renal endpoints (ESRD/ doubling serum creatinine/ renal death). Based on these data we performed simulations for a future trial. We calculated the duration of enrollment and total duration of the clinical trial to accrue 961 endpoints, which provided 90% power to detect a 20% risk reduction assuming a renal event rate of 5.6% (base scenario).
Results
848 patients (median UACR 1239 mg/g; median eGFR 44 ml/min/1.73m2) were eligible for the base scenario. Lowering the UACR qualification threshold increased the number of eligible patients (thus decreasing screen failures) and resulted in only a modest decrease in average renal event rate. In simulations, lowering the UACR cut-off accelerated enrollment and did not increase overall trial duration to reach 961 events.
Conclusion
Relaxing UACR based inclusion criteria in a population with documented UACR levels in the protocol required range decreases screen failure rates without prolonging trial duration. This approach may increase recruitment feasibility and site investigators’ motivation.
Table 1
Observed data in ALTITUDE | Simulations for future trial | ||||
UACR criteria qualifying visit (mg/g) | Eligible patients (N) | Renal events (N) | Renal event rate (% per year) | Duration enrollment (months) | Clinical trial duration (years) |
300 | 848 | 117 | 5.6 (4.6-6.7) | 24.0 | 4.2 |
210 | 923 | 122 | 5.3 (4.4-6.4) | 21.9 | 4.3 |
150 | 958 | 126 | 5.3 (4.4-6.3) | 20.9 | 4.2 |
30 | 988 | 129 | 5.3 (4.4-6.3) | 20.0 | 4.2 |
0 | 995 | 129 | 5.2 (4.4-6.2) | 19.8 | 4.2 |